Batteries? Start and House

[FarmerFrederico]

I think I'll go with some AGM 6V's for my house batteries by Crown. I found them online. I'd spend about $500 for a 220aH bank and about $1000 for a 390aH bank. I'll keep the winch and compressor on my starter batteries. If I'm using a maximum of 85aH/day and more realistically about 40-50aH/day, should I save my money and go with the smaller bank? I have a 150W panel that produces 8amps. Handy Bob says, "Regardless of how much power you use, you need nearly 3% of your total battery storage amp hour capacity in charging amps in order to successfully charge those batteries. With less, you can’t equalize." I'd be in the safe zone with the 220aH bank because I only need 6amps for that bank, while I'd need 11amps (a second panel) to successfully charge the 390aH bank under his philosophy.

What do you guys think, should I save my money with the size of system I'm realistically going to use in this van? I'm not watching TV, or microwaving, or using an electric kettle. I do like overkill, but from what my research is telling me, 390aH is overkill for my needs, don't you think?

 

[FarmerFrederico]

I've got a temperature controller too! Here is the system I'll be using, luthj - http://www.bogartengineering.com/products/

I guess I drank the Handy Bob kool-aid. Think I'll order up the 220aH AGM bank by Crown. Going with Odyssey AGM group 65 for the factory battery locations - can get them for a good price - about $300 less for the pair than something by Lifeline.

 

[luthj]

390AH is definitely more than you need right now. I have installed/designed a few systems similar to yours, and 225-250AH is usually just fine. If you plan on camping for long periods without driving, you may find the 150W panel inadequate for keeping up with your fridge. There are too many factors to know for sure at this point. With a good alternator charging setup, you can get more AH faster using a larger bank. Larger banks will accept more charging current, especially in the bulk phase. This can be helpful when you need to make up lots of AH in a short drive. A larger bank could be used to run your compressor for longer without starting the engine. This may be important in some situations where you don't want to idle due to fumes or noise.

AGM batteries do not need and should not get an equalizing charge under normal conditions. Equalize charges are mostly used on flooded batteries to prevent stratification. In some applications the "equalize" (higher voltage absorb) charge is used to ensure full charging. This is usually when a bank is not charged to 100% daily. For example in marine applications where running the generator for 2-3 hours extra every day is not reasonable.

I see no issues with a 300-400AH battery bank and a smaller solar setup. Especially AGM which charge more efficiently. The only problem you might run into is that you will be tempted to use more AH than you have available in charging. This just means you might need to plug in a wall charger when you park the van occasionally, or get out your second panel.

Crown makes good batteries, but you need to consider you usage before shelling out the cash. If you are only using your van a few times a year, it probably is not worth the cost for high end batteries. They age somewhat, regardless of usage. If you also think you will abuse them (poor charging, discharging to lower than 80%) going cheaper is probably best.

I went with lifeline batteries for my house bank (510AH) because they offer very good cycle life, and they recharge very quickly (even from my 14V alternator). They also have great AH ratings from fairly small packages.

Regarding your solar controller. I did a quick look at there specs, there profiles may not have high enough absorb voltage. Check the battery manufacturers specs against the bogart documentation. 14.2V absorb is too low for many AGM batteries. Make sure that the controller has a profile (or can be custom programmed) that matched your battery choice.

Any good quality starting battery will work for your Chassis system. Since you are using a winch, make sure all your wiring is sized correctly. No reason to risk a fire.

 

[FarmerFrederico]

If you take a look at their controller specs - it's highly customizable http://www.bogartengineering.com/wp-content/uploads/docs/SC2030-9-10-15-UsersInstruc.pdf

I just spoke with Bogart and because the Crown1 is such a new AGM they don't have a lot of info on it. He recommended the Concorde Sun Xtender AGM because they have been very communicative in providing recommendations for charging profiles. Bulk charge for that battery would be at 14.3V and then to finish it off it would go all the way up to 16.5V for the last 2%.

The only thing I have happening in the back of my mind though is that I'll essentially be tying my house battery bank to my chassis battery bank in order to get a charge from the alternator. How do I protect my chassis battery bank from higher charge voltages from the solar charge controller? Will a Blue Sea ACR do this? Or is the short amount of time 16.5V is being introduced into the system not a problem?

 

[luthj]

Anything over 16V or so should be isolated from the chassis electrical system. The blue sea ACRs will normally open and lockout over 16V. In your case using a regular dumb relay/separator tied to the ignition would work. An ACR with bi-directional sensing would not be ideal in your case. One way sensing ACRs would work though. These types of ACRs will only look for charging voltage on the vehicle side, and ignore charging on the AUX side. I believe surepower makes one way sensing ACRs. Here is one.
http://amzn.to/290WuxQ

Some chargers/monitors have the ability to drive an output based on SOC or voltage. If yours has this you can use it to disable a bi-directional ACR during the final charging phase.

 

[FarmerFrederico]

I think I found my house battery - http://www.sunxtender.com/solarbattery.php?id=10 Single 12v 212Ah - should fit in my most desired spot on the passenger side frame rail, can easily fit in my second favorite spot where the spare tire used to go.

Now for the last bit of research on the separator.

 

[Paddy]

How much? Looks nice. I bet it's expensive though.

 

[FarmerFrederico]

How much? Looks nice. I bet it's expensive though.

$518 is the cheapest I can find it before shipping - it doesn't require HAZMAT for shipping so it shouldn't be too much. I like your idea about the lithium bank, but I already bought into a charge controller and battery monitor that is tied to lead acid / AGM battery charging profiles.

 

[luthj]

That is a good sized battery. An 8D size would get you 250AH if you can make it fit.

I ordered 2 lifeline 8D batteries for my van. They were $750 each delivered to my local battery store. Might be worth checking the pricing on lifeline units before you pull the trigger. The batteries are heavy enough that they will likely have a lift gate fee if you delivery them to a residential address. Having them shipping to a area with a loading dock or forklift might save you $50.

 

[FarmerFrederico]

So I decided to go with a single 12V AGM battery. This will simplify wiring, and AGM's stand up to vibration better too. Another reason I went with the AGM is that for simplicity and time's sake I've decided to put the battery inside the van instead of underneath. This will allow me to get up and running fairly quickly because I'm kind of pressed for time in making decisions around a battery box mounted below. The AGM won't off gas so that is important as well.

I've narrowed it down to these two batteries:

http://www.solar-electric.com/concorde-sunxtender-pvx-2580l.html Concorde 258Ah for $855 delivered to my house. $150 is delivery. Made in USA

http://www.solar-electric.com/unba250amagm.html Universal Power Group 250Ah for $550 delivered to my house. $100 is delivery. Made in China

Anyone have any thoughts on which one I should go with? I can afford the more expensive battery but it's always nice to save some $$$. Am I missing something or are there a lot of people running two 100+Ah 12V's in parallel for much cheaper?

I don't think I'll be abusing the battery - it should almost always be topped off with the solar available on the Front Range here in Colorado. I think I'll have the ARB 62qt fridge running nearly 24/7 so that the kiddo and I can head out quickly for day trips to the bike park or up the mountain and just throw food in the fridge without thinking twice, I can also keep 12 beers in there at all times so that I'm never without a frosty beverage at the trail head every again. I'm thinking I can also set the thermostat for the MaxxFan at about 90 degrees to keep the interior from baking - I've got Reflectix coverings for all my windows and will be adding Thinsulate backing to them in the future too. With an additional standalone Fantastic Fan I think I could crack the windows open and keep our dog cool in the van on all but the hottest of afternoons so that it would be easy to have him along with as well. He sometimes gets left at home because he can't participate in all of the errands or adventures we take places without a cool place to chill.

Still haven't decided on an isolator to use in connection with the Bogart Solar Charger so that I can tie the house battery to the alternator as well.

Any input is appreciated?

 

[luthj]

How many years do you plan on having this battery? Judging from your description, your usage will be quite light. In this case, I doubt you will see the benefit from the more expensive (and better quality) sun extender battery. The better battery will get much longer cycle life. But given your low usage, it may not matter.

The Concorde batteries (same company that makes lifeline batteries) indicates you can expect 1000 cycles at 50% DOD. Note that the battery will still work after 1000 cycles, but that its capacity will be 80% of new. I know of several installations where the lifeline/concorde batteries are 7+ years old with over 2k cycles to various DOD, and still going strong.

http://www.solar-electric.com/lib/wind-sun/techmanual.pdf


Here is a uni directional battery separator. It can be wired to that is only senses voltage on the engine side. Whenever the alternator is running (over 13.2V) it will close allowing the Aux bank to charge. It does not have a high voltage cut-out though. Which may allow it to remain open after turning the engine off?

http://www.allbatterysalesandservice.com/browse.cfm/4,2705.html

Another option is just a dumb/simple relay. Wire it to the ignition on feed (find one that is powered AFTER start, not during the key-on), and it will close whenever the engine is running. And open when its off.

This one is beefy enough to allow starting your engine from the aux battery (assuming correctly sized wire/fuses)
http://amzn.to/29SEoA9

 

[Paddy]

I have the battery doctor version of that and yes they do remain connected after the engine is off, until the total combined house/engine battery is dragged down to 12v in my case. I like that yours switches off at 12.8 because mine can remain connected for a long time, diminishing my engine battery somewhat. Always starts in the morning though.

 

[Bikersmurf]

I just saw Interstate golf cart batteries at Costco in the US. If I was buying new house batteries that's the way I'd be going if I lived in the US. $83x4... I though I saw 230AH but that doesn't seem right. Can't see how you could go wrong with interstate (unless quality has been slipping)

I know AH stays the same in series... With the 4, it give me at least the 220 AH I had... Anyone know how much current they can handle?

I switched to 12v starting batteries this round because the warranty is better, and the pervious batteries died outside of the 12 month replacement period... 3 years free replacement works better, and so far they seem better able to handle inverter demands and charging amperage. (215 amp alternator)

 

[luthj]

Golf cart batteries are quite robust, and do work well. They can be used inside the van, but the odor during high voltage charging can bother some. The explosion risk is pretty much nonexistent with modern controllers, as they do not charge for extended periods at high voltages (which produce lots of hydrogen gas). This doesn't affect AGM batteries though.

Starting batteries will provide very limited life as deep cycle batteries. For some the usage is low enough that it doesn't matter.

The GC2 6V batteries will be about 225AH with 2 batteries at 12v (series). For 450AH you can go with 4 batteries in a series-parallel configuration. These batteries can be charged at high rates without damage (assuming a temperature compensated charger. You can usually charge with a C/2-C/3 rated charger. brief charging with much higher currents is possible (C/1).

Just because the alternator is rated at 200A doesn't mean the batteries will charge at that rate. The wiring resistance (including ground/negative), battery chemistry, SOC, and temperatures all play a roll. For example, my 510AH AGM bank with 2/0 charge cable, and SOCs below 80%, will pull over 90A when charging from my 200A alternator at around 14.1V.

If your batteries are dying prematurely they probably are not getting charged correctly. Lead acid batteries need to be charged to 100% (no just 99%) regularly if they are going to survive. The alternator is good for bulk charging, but it is not high enough voltage for absorb charging of deeply cycled batteries. For this you need a separate charger. A 120V shore power unit, solar, or Sterling battery to battery charger (these are expensive).

I repeat, the alternator alone is not sufficient for recharging deeply cycled batteries. They will sulfate and die prematurely. At a minimum (any time you are cycling the batteries) they need to be topped up (brought to 100% SOC) with a quality charger once a week or so (more is better). If the batteries are not being cycled, and are fully charged, you can forgo this and let the alternator keep them topped up (float charging).

 

[Bikersmurf]

I nightly plug in the batteries to shore power. I've now paralleled 2 of the 3 legs of the charger to ensure the house batteries reach full charge nightly. Previously the one leg didn't always get the batteries to 100% nightly.

They don't get cycled that deep or often so the batteries I'm running should be fine, and besides for about $200 I've got replacement batteries for the next three years. If they die within 3 years, I get 3 more years free.

As for charge, between the 4 batteries (2 house & 2 Start) I routinely see 200+ amps charge for the first 10(or so) minutes of driving after that it comes down. About 50 amps is for the starting batteries but that leaves about 150 to the 2 house batteries.